This invention relates to the production of woven fiber reinforcements for structural components, and is particularly concerned with the provision of a three-dimensional non-crimp integral woven fiber reinforcement for structural components, such woven reinforcement being subsequently impregnated with a resin, followed by curing the resin to form the structural component.
Most shaped structural type composite parts are made from multiple plies or layers of "B" stage epoxy resin impregnated woven cloth or unidirectional type fiber (graphite, boron, Kevlar, fiberglass, or mixture of such materials). Shaped parts such as channels, I-beams, "J" sections, etc. are laid up one layer at a time on a tool until the total number of plies have been positioned to a prescribed fiber ply orientation pattern. This layered assembly is then impregnated with resin and cured under heat and pressure by conventional processes, dependent on the resin system in use. These fiber reinforced resin or plastic components have numerous applications, particularly as structural components in airplanes, ships and automobiles.
However, the individual ply-by-ply layup time for assembling a required fiber pattern is time-consuming and expensive, and further is subject to human error in fiber ply count and fiber ply orientation.
Many prior art patents disclose the production of various forms of woven and unwoven materials or cloths which are impregnated with resin. Many of the resin impregnated structures so produced, however, are not designed for use as high strength structural components, but are employed in other applications, for example as acoustic materials.
Thus, for example, U.S. Pat. No. 3,481,427 describes a three-dimensional woven fiberglass fabric which when impregnated with resin and cured, gives a rigid porous panel structure for acoustic requirements. A sandwich with porous skin on one side and solid skin on the other side, and connecting fluted webs, can be woven at once. The weaving is in the form of an over/under pattern that is not optimized for strength but for sound absorption.
U.S. Pat. No. 3,700,067 describes a three-dimensional woven porous face sheet formed from an integrally woven fiber which when impregnated with a low flow resin and cured, gives a rigid yet porous panel. Its intended use is sound absorption.
It is accordingly an object of the present invention to provide a woven fiber reinforcement as an integral assembly, which can be impregnated with resin and employed as a structural component. Another object of the invention is to provide a three-dimensional non-crimp woven fiber reinforcement as an integral assembly or unit, which can be impregnated and cured to form structural components. Yet another object is the provision of the above noted three-dimensional woven fiber reinforcement in one piece, which can be formed into various types of structural shapes, such as an I-beam, such woven reinforcements having high modulus and high strength. A still further object of the invention is to provide the above noted woven fiber reinforcements in an integral shape by inexpensive and simple, e.g. automated, weaving operations.